An information apparatus such as the printer and the copier is equipped with a group of control programs for executing control of the operation of the apparatus. These programs are generally called a “firmware” in that they lie somewhere between a hardware and a software. It is not as easy to change or modify these programs, as it is to upgrade a program in an information apparatus such as the personal computer.
Thus, the only way to change or modify the “firmware” conventionally, was to remove the EPROM (erasable and programmable read only memory) which is on the board inside the apparatus such as the printer or the copier and stores the control programs, and replace the EPROM with another EPROM that stores new control programs.
However, replacing the ROM is troublesome in that the housing of the apparatus has to be removed. As a result, a new method has become more popular, which is a method of storing the control programs beforehand onto an EEPROM (electrically erasable and programmable read only memory) that is electrically rewritable byte by byte or onto a flash EEPROM that is rewritable by all bits or block by block, and, if an update is required, obtaining the latest program(s) from, an IC card installed in an IC card slot, or a host computer connected via a network such as the Internet.
In this method, firstly the CPU in the apparatus reads the programs stored for example in the flash EEPROM out onto a RAM and executes them sequentially to clear the programs stored in the flash EEPROM. Secondly, new control programs are received from an IC card or a host computer and written onto the cleared flash EEPROM.
Examples of the above method are disclosed in the Japanese Laid-Open Patent Publications Nos. 07-073042, 08-101794, 08-123235, 08-166883, 08-305561, and 11-184708.
Unfortunately, in the above-described conventional method, if there is a system crash due to an electric power failure or because the power is turned off by mistake, after erasing the programs in the flash EEPROM and before writing a program onto the flash EEPROM completely to the end, the once cleared flash EEPROM is left with no program or at least no complete program.
The only way to fix the system crash is to get a technical service man to replace the flash EEPROM directly mounted on the board, together with the board itself. This results in extra costs, which are spent on the service and components required for the replacement, also at the cost of not being able to use the apparatus while the system is out of order.